Inflatable plugs are used for plugging pipelines such as sewer lines to permit pipe maintenance, facilitate toxic waste containment, or remove blockages. Such inflatable plugs include inflatable rubber pillows or cylinders which are inserted into the pipeline and inflated with air so that they will fill the pipeline and function as a plug.
One prior art inflatable plug includes an inflatable heavy cylindrical rubber plug having a size only slightly less than the internal diameter of the pipe to be plugged. An example of such a plug is manufactured by Vetter, Zuelpich, West Germany. Such inflatable rubber plugs are inserted into a pipeline or sewer line and then connected to a source of air pressure so that they inflate slightly to fill the pipe. One of the uses of inflatable plugs is in the handling of liquid waste accidents. In the event of a liquid waste spill, an inflatable plug can be inserted into a sewer line to prevent the liquid waste from entering the sewer system. The liquid waste can then be pumped into a proper holding vessel and disposed of.
Another use of inflatable plugs is in repair of broken sewer lines, water lines, or other pipes. The plugs can be inserted into the sewer lines or water lines upstream of the break to thereby block that pipe and permit repair of the break.
Still another use of inflatable plugs is in clearing a blockage in a pipe. An example of such a plug is shown in applicant's U.S. Pat. No. 3,714,951, showing an inflatable drain cleaner which uses water pressure to remove an obstruction from a clogged drain. This type of plug includes a conduit passing through the plug and allowing fluid to pass therethrough. When the plug is inflated by fluid pressure and lodged in place, pressurized fluid is also discharged from the end of the plug thereby clearing the blockage from the pipe.
Because of the wide variety of sizes of sewer pipes or water pipes, if prior art inflatable plugs are to be used, it is necessary to have on hand a number of plugs of varying sizes.
Another drawback of prior art inflatable plugs is that they are relatively large when compared to the size of the pipes being plugged, and they are also comprised of relatively inflexible material such that they may be difficult to insert into the pipe. For example, in the case of a horizontal pipe, it may be necessary to insert the plug vertically downwardly through a manhole and then turn the plug 90.degree. such that it can be inserted horizontally into a pipe. Due to the large size and relative inflexibility of the prior art inflatable plugs, such manipulation of the plugs may be difficult, particularly in the case of a liquid waste spill where time is essential.
Another drawback of prior art inflatable bags is that they are typically comprised of one or more pieces of elastic material joined at a seam to form an enclosure. This seam can provide a weak point which may fail under pressure, causing a failure of the plug.
Attention is also directed to the pillow-shaped inflatable pipeline plugs manufactured by Circle Gas & Manufacturing Co., Scranton, Pa. and to applicant's U.S. Pat. No. 4,565,222, showing an inflatable apparatus for use in plugging a large diameter pipe. Other related devices are shown in the Anderson U.S. Pat. No. 3,086,540; the Lasting U.S. Pat. No. 3,075,535; and the Amet U.S. Pat. No. 1,308,469.